import math
x1, y1, x2, y2 = map(float, input().split())
print(f"{math.sqrt((x2-x1)**2+(y2-y1)**2):0.9f}") import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 print(f"{math.sqrt((x2-x1)**2+(y2-y1)**2):0.9f}") print f"{math.sqrt((x2-x1)**2+(y2-y1)**2):0.9f}" y2 = map(float, input().split()) map(float, input().split()) y2 x2, y2 = map(float, input().split()) map(float, input().split()) x2 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1
import math
x1, y1, x2, y2 = map(float, input().split())
print(f"{math.sqrt((x2-x1)**2+(y2-y1)**2):0.9f}")
